Starting device for electric motors.



B. T. MCCORMICK.

STARTING DEVICE FOR ELECTRIC MOTORS.

APPLICATION FILED FEB. 21. 1917 1 1 96,254. Patented Aug. 29, 1916.

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elates to starting rievicee 111v elated 1 oavy 'eccired. tc or previ zieti wi h a .3 means of an induction oumi rotor type, a great in such case it is nece the seconciary circuit of ecticn. motor "with a com resistance. If the starting ere cast-iron gricis it and expensive.

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q w m 5. e 2e @acb oe the case, a. is the obgeet oi my 111*? A. on pyovlde startmg iiewces Icc'r electric meters in which the resistance is of maximum value, minimum. in Weight and which occupies a minimum. amount of space. A further object of my invention is provide a starting device'ltor electric motors which is simple, compact, and durab'ie, meetthe requirements of commercial op various navel features of my inven- Ie be apparent from. the ciescription drawings, and will be particuiarly set J21 tee appended? claims.

invention is illustrated on the acccmcg" sheet drawings, in Which- F1 me is a iongitudinai sectional View the line 1-1 of Fi 2 of a unit starting device. Fig. 2 are. cf said unit; and, Fig. 3

View disclosing a rotorction motor, the secondary of ed with my new rheostatic IwMICK, OF MfiNTlit-Eik 'll, QLYEEEG, CANADA, ASSIGNOR; BY MESIQi AIJLI CHALMEHS MANUFACTURING COMPANY, CORPQRATIQX uted Aug. a1 F'o. 679,134.

cievice, three of the l and 2 bemg connectefi. in

As shown in 3 of the drawings, the incuction motor 19 supplied from 11, 12, and 13, and the secondary circuit of said. meuctlou motor is connected. ti

e r; a l to a starting, device c: 153-, which 1 1 Mates tbsee e inter-c eiariec'ixec of said.

cu: er cu ts var: sta. 111g of operating com the incluction meter. A. we inductio e may be for cirivii J my ioaci it is adapted.

"Where an imiucticn meter is used for starting up systems of great inertia, such as generators or motor-generator sets equipped with heavy fly-Wheels, it is necessaryithat the secondary circuito f the induction motor be provided with an. adjustable resistance of comparatively high value. The commercial problem is to produce the lightest anci mos eiurabie resistance having maximum desired vaiue and which occupies space. To meet all of tbese desirable features, I have previcied a resistance preferably in the form of a bellow member 0r seamless tube or coil 17 of small cross-sectional area, which is supportedin a frame 18 suspended from a cover 19 of a tank'QO. The tube 17 is pref. erabiy in the form of a coil and passes through openings 21 in the members 21 forming the sides of the supporting frame 18, which, being suspended from the cover, can be removed with the resistance coil 1? as a unit frcm the tank at any time Prefeabiy, each unit as. shown in Fig. 1 forms one leg of an interconnected resistance in the secondary circuit the induction motor. In other WOI'dS, the starting 'z'esistanee includes three of the units iilustra es in Fig. 1- The resistance coii 17 is prcviciec'i with a plurality of tape 22 from which leads 2' extend to contacts 2 L 0.1.1 the face plate of? the rheostat. These leads pass through the cover 19 of the tank 20 and are insulated. therefrom by bushings 24. Within the tank the leads 23 take the form of rods which are supported at one end in a 1me1nber 25 which forms the bottom portion. of the frame 18.

Preparatory to ing the motor 10 with its load, the tank 2c is filled with water or any other'fiuid cooling medium through inlet 26, which is provided with a valve 27. The water or insulating fluid com pletely immerses the resistance coil, and the level of the cooling medium, if it be a liquid, can be observed from an indicating gage 28 connected to the upper part of the tank 20. In the commercial design of such a resistance, it is intended that the tank shall hold enough water to absorb, without reaching the boiling point, the total amount of energy for startir the motor under the most extreme conditions. When the motor has come up to speed, the water thus heat ed is drawn out through an outlet 28, which is provided with a valve 29. The hollow member or tube forming this resistance gives a small crosssectional area for the sistance of current and a large contact area for the transfer of heat, thus permitting a high resistance with a relatively short length of conductor and a large contact area of water surface. The latter is increased by providing the tube with openings or holes 30 so that the cooling fluid may be in contact with the inside of the tube as well as with the outside thereof. It is to be noted that with this type or" rheostat there is a storage of energy in the water during the starting period, and that the water is drawn of? after the motor has been started and replaced by a fresh supply of cold water so that the rheostat is again ready for use.

There may be various modifications in the precise form and arrangement herein shown and described and I aim to cover all such modifications which do not involve a do partu're from the spirit and scope of my in vention as set forth in the appended claims,

What I claim as new is;

1. In a rheostat, a fluid-containing tanlr having a cover, a frame supported by" said cover, said frame comprising a plurality of angularly spaced members, a hollow re- 'sistance coil having openings and mounted on said frame, and leads extending from different portions of said resistance coil.

'2. In a device otthe class descrihed, a tank, a cover therefor, a frame mounted on said cover in position. to be suspended. in said tank when said cover is in place there on, a coil peripherally supported on said frame, and a plurality of terminals extending through said cover, two of said 0. heing connected to the ends of said in a rheostat, the combination of a tanlr and a cover therefor, a. resistance element mounted on. said cover so as to be containedwithin. said tank when said cover: is inv plus, said resistance element comprising coil. of hollow perforated tubing, and ter minal members (J u |v v 0 con and a plurality of terminals disposed 7 of said coil.

ostat, the combination of a terminals, resistance elements between adjacent terminals, said elements of sections of coil, "fillllQClllQl'iS minals an mroon points ctions being ii, supporting means for said coil engaging .l coil along the periphery thereof,

6. in a device of the class described, a tank and a cover therefor, a resistance element comprising a single coil, means for supporting said coil in position in said tank when said cover is in place on said tank comprising a plurality of angularly spaced members supported by said cover and en gaging a plurality of peripheral points along said coil, and a plurality of terminals mounted in said cover and connected with said coil at different points '7. in a rheostat, the combination of a receptacle, a cover therefor, a resistance elemerit in the form of a helix mounted in f. receptacle with its axis perpendicular to the plane oi said cover, supporting means for resistance element mounted on said cover, a plurality of terminals passing into said receptacle and extending into engagement with different portions of said coil, said supporting means and said ter minals heing disposed within the helix formed hy said resistance element.

8. in rheostat, the combination of a receptacle, a cover for said receptacle, a resistance element in the form of a coil mount V in said receptacle with its axis sulo stantially perpendicular to the plane of said cover, supporting means for said coil mounted on cover, and a plurality of terminals mounted on said cover, extending into said recep acle and connected to spaced portions of said coil, said coil, coil-supportoi coil and engaging points along ing means and said terminals being removable from said receptacle with said cover.

9. In a. rheostat, areceptacle adapted to contain liquid resistance material, a cover for said receptacle, a resistance coil adapted to be immersed in the resistance material in said receptacle and having its axis perpendieuiar to theplane of said cover, and leads entering said receptacle through said 10 coves and connected to spaced portions of said coil, said coil and said leads being removable from said receptacle with said cover. 7

Milwaukee, Wis, J an. 8, 1912. In testimony whereof I affix my signa- 15 ture, in the presence of two witnesses.

BRADLEY T. MCCORMICK. Witnesses:

G. PERCY COLE, JEssm M. ALLAN. 

